We are definitely going to have to give you an A++ for dedication and determination. A lot would have given up or put it aside by now but every day you kept trying something new. Watching it run now you have a very sweet running engine. If you decide to build another one I can only imagine how much sweeter it would be after having learned so much from this one. Thanks for letting us look over your shoulder as you built this one.

Cheers

Don

Logged

Good, better, best.Never let it rest,'til your good is better,and your better best

As a matter of course, I would suggest the nut would work just fine, but only needs a drop of locktite to keep it retained. I've been building Harley engines for some thirty odd years and the only thing that keeps all their parts on the engine is locktite or self-locking nuts, cotter keys, bunged up threads and the like. As a rule of thumb for an engine, a carb bore of a quarter the cylinder bore is usually a good size to start with. This works well with multi-cylinder engines as well, as only one cylinder is fed at a time. A smooth venturi with a good taper leading up to it helps keep a consistent vacuum to pull fuel in as well. For what its worth,mad jack

I've tested sparking plugs with those ceramic rings, and they definitely don't wear out as easily as ptfe.

On the other hand, as this engine is on the experimental state, even the spark plugs need to be easily disassembled and cleaned, if needed.

Using ceramics doesn't make that easier. Not to mention, that it's quite delicious delicate job to make parts from it, that fit. Plaster anyone?

Big white is the resistor body, that was originally attached to an automotive ignition coil, that I use. Next is one of the spark plugs.And the marble looking thing is just one of the rings, that I managed to hack out of that big white. Bluish colour comes from felt tip, that I used to mark, where the cut was made.

Conclusion at this point is, that the engine still runs at too rich fuel mixture, causing contamination on the sparking plug rather easily.

--------------------------------Mad jack, somehow that cyl.bore/4 = carb bore makes sense, as it says, that I'd need to enlarge current carbs throat from 1.9mm(~0.075") to 2.6mm(~0.102").

Somebody over on HMEM just finished an i.c. engine and used the vapour carb with really good results. He also tried the same tank / carb on his hit & miss engine and that ran really good too, so much so that he is making another jan ridders vapour carb for that too!

I think you need to find where the blowback is coming from and get to the route cause - there must be something leaking on the compression stroke for that to happen. I would try submerging the engine in water, turning it over past the compression cycle and look for the bubbles.

Another strange phenomonen. I know I keep banging on about Jan Ridders engines, but this is because he has build a lot and done a build log of his findings with all of them. I noticed on a couple of his engines he has some sort of additional chamber with check valves in line. Not quite sure why they are needed without reading through it again but they are!